Communications terminal

ABSTRACT

A communications terminal is provided which includes an antenna element, which has a specific antenna volume, and an acoustic output device, wherein the antenna element and the acoustic output device are designed and/or arranged with respect to each other such that at least part of the antenna volume forms at least part of a resonant cavity for the acoustic output device.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a communications terminal havingan antenna element, which has a specific antenna volume, and an acousticoutput device.

[0002] In the development of modern communications terminals,particularly mobile handheld devices such as mobile phones, palmtops orPDAs (Personal Digital Assistants) having appropriate mobile radiofunctions, minimizing the overall dimensions of the device isincreasingly important. At the same time, the device is meant to offerever more facilities with ever better quality, including optimizing thereproduction quality of the transmitted signals. Apart from improvingthe microphone of the transmitting communications terminal, this alsorequires the best possible transmission quality of the signal over theair interface, and a qualitatively good acoustic output device in thereceiving device.

[0003] Crucial for the transmission quality of the signals over theradio network are the antenna elements used by the device. In order toradiate and receive electromagnetic radiation in a specified frequencyband, such an antenna element defines and requires a certain space,known as the “antenna volume”, which must be kept as clear as possibleof obstructions to avoid effects on the antenna characteristics. Sincethe antenna elements in more modern devices are preferably integrated inthe device, the communications terminal takes up a larger amount ofspace. In addition, the requirement for communications terminals withdual-band capability or multi-band capabilities means that the antennasneed to occupy even more space. Thus for given outer dimensions of theoverall device, improvements in other components, which are againassociated with an increased space requirement of the componentsconcerned, are generally only possible by, for example, reducing thespace for the antenna while accepting a degradation in the antennaproperties.

[0004] An object of the present invention, therefore, is to create analternative mobile phone to the state of the art, which with minimumpossible dimensions provides a good antenna transmission quality whilealso providing a good acoustic output quality of the received signals.

SUMMARY OF THE INVENTION

[0005] According to the present invention, the antenna element and theacoustic output device of the communications terminal are designedand/or arranged with respect to each other in such a way that at leastpart of the antenna volume forms at least part of a resonant cavity forthe acoustic output device; for example, an earpiece. As a result of thepresent invention, the space available in the communications terminal isutilized very effectively in that the space required for the antennafunction is simultaneously optimized and designed as a resonant cavity.As such, the space inside the communications terminal is used for twodifferent functions without impairments to the one function arising fromthe use for the other function. For the antenna function, an air-filledinterior cavity area is optimum, because such an air-filled area onlyhas a small dielectric constant and does not cause any RF losses at all.The acoustics also need as large an air-filled area as possible asresonant cavity for optimum operation; for example, as a “back-cavity”volume at the back of an earpiece.

[0006] Preferably, the antenna element is disposed on an antenna supportcontaining a cavity having an opening on which the acoustic outputdevice is arranged in such a way that the cavity forms the resonantcavity for the acoustic output device. Obviously, the opening may alsotake the form of a number of small holes, a mesh or the like. The cavityshould be substantially soundproof, except for the opening or openingsplaced on the acoustic output device, so that the required soundpressure can be established at the opening(s) on the acoustic outputdevice.

[0007] Such a construction can be achieved, for example, by the antennasupport consisting of a body made of non-conducting, (i.e., insulating),material containing a cavity having the relevant opening. This cavitythen forms the resonant cavity. Since the body is made of non-conductingmaterial, it can lie within the antenna volume. This means that, forexample, the antenna element can be applied outside on the body.Preferably, this takes the form of one or more conducting areas eachapplied to a surface of the antenna support.

[0008] In a particularly advantageous exemplary embodiment, the antennasupport also contains a mounting for the acoustic output device. Thiscan be implemented, for example, by a recess made in the antenna supportinto which the earpiece is inserted and secured.

[0009] In a further preferred exemplary embodiment, the antenna supportalso contains one or more integral screened cavities for screeningspecific areas within the communications terminal; for example, areas ona circuit board that are susceptible to EMC from the RF radiationemitted from the antenna. These screened cavities can be formed byrecesses made in the surface of the body forming the antenna support andcoated internally with a conducting layer, where the antenna supportmust be positioned at the appropriate position on the circuit board sothat the recess covers the area to be screened on the circuit board.

[0010] For maximum efficiency when fitting such an antenna supporthaving the antenna element and the acoustic output device, the antennasupport preferably also contains contact elements for making conductivecontact with the antenna element and/or the acoustic output deviceand/or the screened cavity. The antenna support having the appliedantenna elements, the pre-fitted acoustic output device (or,specifically, earpiece), and the finished screened cavity with theassociated contact elements, can simply be placed as a prefabricatedmodule at the required position on the circuit board during finalassembly of the communications terminal. By designing the contactelements to the circuit board to be elastic so as to create pressurecontacts, other additional work operations such as contact soldering canbe avoided.

[0011] Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

[0012]FIG. 1 shows a perspective view of an antenna module thatbasically includes an antenna support with an applied antenna elementfor fitting in a communications terminal according to the presentinvention.

[0013]FIG. 2 shows a central longitudinal section through the antennamodule of FIG. 1.

[0014]FIG. 3 shows a cross-section through the antenna support of theantenna module in FIG. 2 along the intersection line A-A′.

[0015]FIG. 4 shows a plan view from above the antenna module of FIG. 1.

[0016]FIG. 5 shows a plan view from below the antenna module of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0017] The figures show an antenna module for a communications terminalaccording to the present invention; specifically, a mobile phone. Thismodule has an antenna support 4 which is basically formed as anon-conducting plastic body 11. This antenna support 4 is coated on twoopposite surfaces with specially patterned conducting areas 1 a, 1 bforming a two-piece antenna element 1. The antenna volume extendsbetween the conducting areas 1 a, 1 b. This antenna module is placed insuitable contact with a printed circuit board 20 of the mobile phone atthe intended position in the mobile phone.

[0018] The design and shape of the antenna module are described indetail below.

[0019] The plastic body 11 forming the antenna support 4 consists of twojoined half-shells, which thereby create a cavity 5 inside the plasticbody 11. For good sound quality, the resonant cavity 3 should have amaximum volume. The cavity 5 is therefore chosen to be as large aspossible, while taking care that the remaining wall thickness of theplastic body 11 guarantees sufficient rigidity. With regard to the outershape, the plastic body 11 is designed to fit the case shape, or ratherthe space available in the mobile phone, and the requiredthree-dimensional shape of the antenna element 1 or the antenna volume2.

[0020] Accordingly, the plastic body 11 has a substantially flat side,which is also referred to below as the front face. There is a recess 7in the front face, into which an earpiece (not shown) is inserted atassembly. There are a number of holes 6 between the recess 7 for theearpiece and the cavity 5, so that the cavity 5 forms a resonant cavity3, more precisely a back-cavity volume, for the suitably designedearpiece introduced into the recess 7.

[0021] Beside the recess 7 on the front face of the plastic body 11,there is another recess which forms a screened cavity 8 integrated inthe antenna support 4. Components of the mobile phone that aresusceptible to RF interference and requiring particular protection, suchas a display controller, can be housed inside this screened cavity 8.Components that need to be screened owing to their tendency to createinterference, for instance an output stage of the transmit device whichemits unwanted harmonics, also can be housed in the screened cavity.

[0022] On the rear face opposite the front face, the body 11 is shapedto fit the shape of the mobile phone case. In the present exemplaryembodiment this is a module for a mobile phone having a case with arounded back and top. The rear face, consequently, also is shaped with amatching convex curve.

[0023] The antenna element 1 itself consists of two conducting areasapplied to the front face and back face 1 a, 1 b. These surfaces havethe pattern required for the antenna function. The precise shape, orrather pattern, of the antenna is here arbitrary for the presentinvention and depends on the frequency bands in which the antenna ismeant to work. In the present exemplary embodiment, the antenna is a“PIF” (Planar Inverted F) antenna. On the front face of the body 11, theconducting area 1 b of the antenna element also runs continuously on theinterior sides 10 of the recesses 7, 9 for the earpiece and screenedcavity 8. As such, the this conducting area 1 b acts as part of theantenna element 1, while also forming the screening for the earpiece andthe screened cavity 8.

[0024] The whole module is then placed, as shown in FIG. 2, with part ofthe front face on the circuit board 20 of the mobile phone, so that thescreened cavity 8 is located directly over the circuit board 20, and therecess 7 for the earpiece lies beyond the top end of the circuit board20 within the case of the mobile phone. On the circuit board 20 arecontact surfaces, which make contact with the front-face conducting area1 b of the antenna element 1 when the module is placed on the circuitboard 20. This front-face conducting area 1 b of the antenna element 1is thus taken to the ground potential of the mobile phone.

[0025] Preferably, elastic contacts are disposed on the conducting area1 b that ensure reliable pressure contact with the contact surfaces onthe circuit board 20. The exemplary embodiment shown has multiplecontact points along the periphery of the screened cavity 8 which arepositioned relatively closely to each other so as to ensure that thecavity 8 is screened against RF interference. Metal springs, forexample, or even drops of conductive silicon applied as spot-shapedcontacts, may be used to form the elastic contact points. Of course,instead of the spot-shaped contacts along the periphery of the screenedcavity, a continuous string of conductive silicon or the like also canbe applied.

[0026] In the exemplary embodiment shown, the pattern of the conductingarea 1 b on the front face of the module is chosen so that conductingpatterns 15 having appropriate contact points 17, 18 are also integratedin the module for making contact with the earpiece. These patterns 15also may be elastic metal springs or printed patterns provided with, forexample, an elastic conductive silicon or the like at each of thecontact points 17, 18.

[0027] During operation, the RF signal is applied to the conducting area1 a of the antenna element 1 applied to the rear face of the plasticbody 11. This is done via at least one, preferably multiple contactstrips 13, 14 (three in the present case), which stretch from the rearface of the plastic body 11 around one edge to the front face of theplastic body 11, and are there provided with elastic contact points 12,16, which in the assembled state press onto corresponding contactelements on the circuit board 20.

[0028] In the plastic body 11, there is also a through hole 21 passingfrom the rear face to the front face to accommodate a coaxial connectorfor connecting an external antenna. This hole 21 runs beside the cavity5 and the screened cavity 8, i.e., it has no effect on the resonantcavity 3 nor the screened cavity 8. The antenna support 4 thusadditionally provides a rigid support for the coaxial connector of anexternal antenna; for example, the antenna of a vehicle hands-freedevice. The inner conductor 19 of this coaxial connector is connectedvia a contact strip 13 and corresponding contact point 16 to theconducting area 1 a on the rear face of the plastic body 11 and to thecircuit board 20, so that the RF signal is also present here. The outerconductor (i.e., the RF connector screening), is correspondinglyconnected to the ground potential (i.e., the conducting area 1 b on thefront face of the plastic body 11).

[0029] The introduction of the patterns 13, 14, 15 for the contacts, thehole 21 for the coaxial connector and the openings 6 into the conductingarea 1 a, 1 b normally does not impair the antenna function, since thesepatterns 13, 14, 15, hole 21 and openings 6 are either relatively smallin relation to the overall surface area, or can be taken into accountwhen designing the antenna structure.

[0030] The present invention provides optimum utilization of the spaceavailable in the mobile phone. The necessary antenna volume 2 isadvantageously used for improving the acoustics. In addition, theantenna support provides a screening function for specific areas on acircuit board 20 of the mobile phone, plus a retaining function for anearpiece or a loudspeaker. Hence, a separate mounting for the earpieceis not required, wherein the cost may be reduced. Furthermore, itensures that contact is made reliably and simply with the antenna, thescreening and the earpiece. Using the rigid plastic body 11 for theantenna support 4, onto which the antenna element 1 is applied asconducting areas 1 a, 1 b, also avoids tolerance problems that arise inan antenna construction without extra support. The whole finished moduleis thus relatively easy and economic to manufacture, and can be fittedquickly and without great effort during assembly of the mobile phone.

[0031] Although the present invention has been described with referenceto specific embodiments, those of skill in the art will recognize thatchanges may be made thereto without departing from the spirit and scopeof the present invention as set forth in the hereafter appended claims.

1. A communications terminal comprising an antenna element (1), whichhas a specific antenna volume (2), and an acoustic output device,characterized in that the antenna element (1) and the acoustic outputdevice are designed and/or arranged with respect to each other in such away that at least part of the antenna volume (2) forms at least part ofa resonant cavity (3) for the acoustic output device.
 2. Thecommunications terminal as claimed in claim 1, characterized in that theantenna element (1) is arranged on an antenna support (4) containing acavity (5) having an opening (6), on which the acoustic output device isarranged in such a way that the cavity (5) forms the resonant cavity (3)for the acoustic output device.
 3. The communications terminal asclaimed in claim 1 or 2, characterized in that the antenna support (4)contains a mounting for the acoustic output device.
 4. Thecommunications terminal as claimed in one of the preceding claims,characterized in that the antenna support (4) contains a screened cavity(8).
 5. The communications terminal as claimed in one of the precedingclaims, characterized in that the antenna support (4) contains contactelements (13, 14, 15) for making conductive contact with the antennaelement (1) and/or the acoustic output device and/or the screened cavity(8).
 6. The communications terminal as claimed in one of the precedingclaims, characterized in that the antenna support (4) contains a body(11) made of non-conducting material having at least one cavity (5)and/or one recess (7, 8).
 7. The communications terminal as claimed inone of the preceding claims, characterized in that the antenna supportconsists of two half-shells.
 8. The communications terminal as claimedin one of the preceding claims, characterized in that the antennaelement (1) contains one or more conducting areas (1 a, 1 b) eachapplied to a surface of the antenna support (4).
 9. The communicationsterminal as claimed in one of the preceding claims, characterized inthat the screened cavity (8) is formed by a recess (9) in the antennasupport (4) coated internally with a conducting layer.
 10. Thecommunications terminal as claimed in one of the preceding claims,characterized in that the antenna support (4) contains a recess (7) onthe outer side in front of the opening (6) of the cavity (5) forreceiving an earpiece.
 10. The communications terminal as claimed in oneof the preceding claims, characterized in that the communicationsterminal is a mobile phone.